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Vacuum arcs on graphite cathodes are currently used as sources of carbon ions for the production of diamond-like films in the arc ion-plating (AIP) deposition process. Emission from these cathode sources is concentrated in very localized “cathode spots” having typically 10 (i.m in diameter for graphite cathodes. These spots carry the totality of the arc current, the remaining of the surface being unaffected by the discharge. For electron emission falling in the thermo-field emission mode, extremely high current densities up to 108 -109 Am-2 are induced generating a high localized heat flux to the surface during the spot lifetime. On metallic electrodes, this strong heat flux generates localized surface melting during the microsecond scale spot lifetime. High localized plasma pressures (>10 Atm in the case of copper) were found to exist in the cathode spot volume, leading to the co-emission of micro-droplets of the liquid metal along with the ion beam. more...

Microelectronic processes now involve multilayer structures of different materials. It is important to control accurately the thickness and composition of these materials during their processing. The determination of these two physical parameters are usually performed by Elastic Recoil Detection (ERD), by Auger Electron Spectroscopy (AES) and Transmission Electron Microscopy (TEM). However, these techniques are not suitable for analysis on a routine basis. In this context, a quantitative procedure based on EDS X-ray microanalysis in the Scanning Electron Microscope has been developped because of its availability and its speed of analysis. However, this technique requires several measurement of K ratio taken at different voltages which is time consuming. With the advent of Field Emission Gun Scanning Electron Microscopes (FEGSEM), X-ray line scans taken at low electron beam voltage with an EDS system may be an alternative. In this paper, preliminary results using this technique on multilayered materials are presented.To investigate this characterization technique, a AlSiCu(200 nm)/TiN(95 nm)/Ti(40 nm) multilayer metallization structure deposited on Si substrate was used. EDS X-ray line scans were obtained with a Hitachi S-4500 FEGSEM coupled with a Link ISIS 300 EDS system. more...

Conventional quantitative X-ray microanalysis in the scanning electron microscope or in the electron microprobe is valid for specimens of bulk homogeneous composition and with flat and polished surfaces. Quantitative methods, using X-ray microanalysis and Monte Carlo simulations of electron trajectories in solids, have been developed for the chemical analysis of spherical inclusions embedded in a matrix and for multilayered specimens. In this paper, the effect of porosity and of the size of the pores are investigated concerning their effect on X-ray emission using Monte Carlo simulation of electron trajectories in solids since porous materials are of great technological importance.This new Monte Carlo program uses elastic Mott cross-sections to compute electron trajectories and the Joy & Luo modification of the continuous Bethe law of energy loss and the details are given elsewhere. This program assumes that all the pores are spherical and have the same size. more...

Recent developments in microelectronic devices have increased the need for new investigative techniques. Much of the development on Electron Beam Induced Current (EBIC) occurred in the early 70's. Since that time, much of the work has been devoted to using this technique to investigate defects in semiconductor devices. Less attention has been focused on electrical measurement of semiconductor properties.A digital EBIC method to characterize semiconductors has been developed and is presented here. The sample current is measured using a Keithley 670 electrometer controlled through a GPIB interface by a standard computer. The electron beam from the scanning electron microscope (SEM) is synchronized with the current acquisition. All the acquisition is controlled by a Labview virtual instrument (Figure 1).As an example of the performance of this method, a special sample was analyzed. A novel method of resistless lithography process was developed in our laboratory. This technique is dedicated to overcome limits of conventional resist based electron beam lithography. more...

In recent years, the critical dimension in “Very Large Scale Integrated” devices has dramatically decreased. The microelectronics industry road map predicts that by the year 2000 the critical dimension will be below 250 nm. This reduction in scale will imply the development of new techniques to control the fabrication of such devices. This paper presents a novel approach to characterize VLSI devices based on Monte Carlo calculations. The principle of this technique is to use information from backscattered electrons (BE). The energies of those electrons are related to their maximum range within the structure. Thus it is possible to distinguish the layer from which they are backscattered. In order to collect this information an energy filtered backscattered electron detector must be used.Figure 1 shows a cross section of a structure produces using a typical VLSI process. The two metal layers are usually patterned to define small lines and contacts. more...

Metal matrix composite (MMC) materials are promising materials because of their higher specific mechanical properties (e.g. strength-to-weight ratio) relative to conventional metallic alloys. However, during the processing of these materials, the development of an interfacial reaction zone between the reinforcing material (generally a ceramic) and the metallic matrix may occur, which typically degrades the mechanical properties of these materials if not controlled. Since these interfaces are generally quite small (from 5 to 500 nm), Transmission Electron Microscopy (TEM) is the technique of choice for characterization because of its outstanding spatial resolution. However, specimen preparation for TEM (e.g. ion milling) is quite difficult for MMC materials, due to the combination of two completely different material types, specifically a hard and brittle reinforcement phase incorporated in a relatively soft metallic matrix. Also, since there is only a small amount of the material which is transparent to electrons after specimen preparation, TEM as a materials characterization technique suffers from a lack of statistical robustness, which is a serious drawback.To characterize materials with a spatial resolution close to that of TEM, low voltage field emission scanning electron microscopy is an option because of the small interaction volume of low energy electrons, as well as the small probe size of these microscopes (typically < 5 nm). more...

Scanning Electron Microscopy (SEM) has been widely used to characterize semiconductor materials. Approximately one half of all SEMs are used by the electronic industry. The SEM can be used as a local current source that can be scanned over semiconductor device surfaces. This imaging mode is called Electron Beam Induced Current (EBIC).A depletion zone formed by a Schottky diode is visualized using this technique. This Shottky diode is fabricated by placing a metal contact on a semiconductor surfaces. The work function of the metal and the semiconductor produce an equilibrium contact potential. This potential barrier occurs across a region free of charge carriers and thus an electric field is present. This region is called a depletion zone. more...

In modern materials science, it is important to improve the resolution of the Scanning Electron Microscope (SEM) because small phases play a crutial role in the properties of materials. The Transmission Electron Microscope (TEM) is the tool of choice for imaging small phases embedded in a given matrix. However, this technique is expensive and also is slow owing to specimen preparation. In this context, it is important to improve spatial resolution of the SEM.In electron backscattering images, it is well know that the backscattered electrons have an energetic distribution when they escape the specimen.The electrons having loss less energy are those which have travelled less in the specimen and thus escape closer to the electron beam. So, in filtering the energy of the backscattering electron and keeping those which have loss only a small amount of energy to create the image, a significant improvement of the resolution of such images is expected. New detectors are now under development to take advantage of this technique of imaging. more...

X-Ray microanalysis is now a well established technique to determine the composition and the thickness of multilayer structures of different materials. The most popular software used to quantify such system are based on analytical φ(ρz) curves which are approximation of the x-Ray generation process. The computed φ(ρz) curves of multilayered samples are based on mixtures rules and weight functions which are not always accurate. In this paper, Monte Carlo simulations of electron trajectories in solids are used to compute φ(ρz) curves in multilayered specimens directly and then used to computed the K ratios.To validate this procedure, a TiN(100 nm)/Ti(10 nm) multilayer metallization structure deposited on SiO2(100 nm)/Si substrate was used in conjonction with a TiN(400 nm)/Si standard sample. This system is a very active field of research and development in the microelectronics industry. The thicknesses, composition and microstructure of both systems were fully characterized by Elastic Recoil Detection (ERD), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). more...

This special issue of Microscopy and Microanalysis contains 17 articles from a topical conference on microbeam characterization of nonconductive materials. The conference was held at the Department of Mining, Metals, and Materials Engineering of McGill University in Montreal on August 2–3, 2002, as the pre-meeting congress prior to the Microscopy & Microanalysis 2002 meeting in Quebec City, Canada. more...

This note generalizes the Archard model for electron backscattering. It is shown that the energy-dependent variation of electron backscattering can be predicted.

It is my great pleasure to welcome you in Quebec City for the Microscopy and Microanalysis 2002 meeting. I invite you to participate in the scientific symposia as well as to attend the exhibits. I also encourage you to visit the old town and the Battlefield Park where you can still hear Wolfe's and Montcalm's weapons used in the dramatic battle of September 1759 that changed the history of North America. I am certain that you will enjoy “Québec Joie de Vivre”. more...

Microscopy and Microanalysis 2002 hosted by the Microscopy Society of America (MSA), the Microbeam Analysis Society (MAS), the Microscopical Society of Canada (MSC)/Societe de Microscopie du Canada (SMC), and the International Metallographic Society (IMS) will provide comprehensive Symposia, Tutorials, and Special Sessions covering all aspects of microscopy. Events will begin on Friday, August 2nd with a two-day Pre-meeting Congress chaired by Raynald Gauvin of McGill University entitled “Characterization of non-Conductive or Charging Materials by Microbeam Analysis.” This Pre-meeting Congress will be at McGill University, Montreal, Canada. On Sunday, August 4th, there will be several Short Courses on a variety of topics for those active in teaching, research, and industrial applications involving microscopy and microanalysis. Formal meeting sessions will begin on Monday, August 5th, and will consist of a blend of different presentation formats including Symposia, Tutorials, and Poster sessions that will offer the latest information on cutting-edge discoveries and also provide the opportunity to learn new techniques and procedures. The unique opportunity for “hands-on” learning with state-of-the-art instrumentation will be provided by the integration of the program with the commercial exhibits. more...

The Monte Carlo method is a very powerful method to describe the scattering of electrons in solids. In this computations, the scattering of electrons is often described by the total elastic Rutherford Cross-Sections, given by [1]:where E is the energy of the electron (KeV),Z is the atomic number of the atom responsible for scattering and α is the screening parameter and it is usually given by [2]:Since equation (1) has been obtained using the Born approximation, it is well known that this formula gives innacurate values when the atomic number of the solid is high and/or the energy of the electron is low [3]. In such cases, total elastic cross-sections computed using the Mott's theory are more accurate. Recently, these total elastic cross-sections have been computed [4] using a complex numerical procedure and values for 96 elements for 26 energies ranging from 20 eV to 30 KeV are available. more...

An oxygen plasma treatment of the TiN diffusion barrier prior to Al deposition of an AlSiCu/TiN/Ti structure is studied and compared to an air break process in order to determine the reactions occurring at the Al/TiN interface as well as the mechanisms responsible for the improved barrier performance using an ex situ and an in situ oxygen plasma, respectively. Various experimental techniques such as grazing angle x-ray diffraction, elastic recoil detection and field emission scanning electron microscopy were used. The ternary and quaternary phase diagrams were used to predict the phases formed. It is first observed that an oxygen plasma increases the oxygen concentration at the Al/TiN interface as well as in the TiN barrier. It is conjectured that first the oxygen reacts with Ti in order to form Ti oxides in the TiN grain boundaries and on the TiN surface. The Al film then reacts with this Ti oxide layer in order to form an Al2O3 layer upon sintering which in turn acts as an additional diffusion barrier a... more...

We report on a study of the fabrication of submicron silicide structures with a resistless lithography technique. Several different metals can be used as a basis for producing silicide using this method; in this work, results will be discussed for both platinum and nickel silicide. The feasibility of producing nanostructures using polycrystalline silicon as a base growth layer for metal–oxide–semiconductor, and other device applications have also been demonstrated. Threshold doses for this method for submicron lines ( more...

In this work, the hydrothermal synthesis and stability evaluation of mansfieldite (AlAsO4·2H2O) is described. The synthesis involves hydrothermal precipitation at 160 °C from equimolar (CAl = CAs = 0.3 M) Al (III) – As (V) nitrate solutions over a period of 24 hours. X-ray diffraction (XRD) characterization showed the synthesized mansfieldite material to have the same structural characteristics (crystal lattice parameters) with the mansfieldite mineral. The product, upon examination with field emission gun scanning electron microscope, field emission gun variable pressure scanning electron microscope and field emission gun transmission electron microscope, was found to consist of individual crystals of 1 to 4 μm.Long term leachability studies (up to six weeks) in the pH range 5 to 9 at 22 °C determined mansfieldite to be more reactive than scorodite and hence not a satisfactory carrier for the fixation of arsenic in the environment. more...